Sky gazers in the UAE will be able to see a unique celestial event on Friday, when the crescent Moon will be illuminated by sunlight reflected off the Earth.
The Earthshine phenomenon, also known as the “da Vinci glow”, will be visible in UAE skies shortly after sunset at 6.48pm.
It received its nickname from renowned 16th century artist Leonardo da Vinci, who helped solve the mystery of why the Moon remains illuminated as sets on the horizon.
“Earthshine … [is] sunlight that's been reflected off of Earth, then bounced off the Moon and back to our eyes,” Nasa said on its website.
“Earthshine is easiest to observe in the few days before and after a new Moon, when the part of the Moon that's directly lit by the Sun appears as a slim crescent.
“Leonardo da Vinci explained the phenomenon nearly 500 years ago.
“He realised that both Earth and the Moon reflect sunlight. But when the Sun sets anywhere on the Earth-facing side of the Moon (this happens every 29.5 Earth-days) the landscape remains lit – illuminated by sunlight reflected from our own planet.”
Earthshine is at its most intense in April and May, when it is about 10 per cent brighter than average as that is when the most sunlight is being reflected off of Earth.
While Leonardo was right about the glow, Nasa said one of his sketches had two incorrect facts, including that the Moon had oceans and that the Earth's oceans were the primary sources of Earthshine.
Nasa explains that clouds on Earth are also a source of the glow and that the “lunar seas” on the Moon are made of ancient hardened lava, not water.
“Earth shines because it reflects sunlight, and clouds do most of the reflecting. When Apollo astronauts looked at Earth, the oceans were dark and the clouds were bright,” Nasa said.
“But these are quibbles. Leonardo understood the basics well enough.”
